Children who live with a substance-abusing father often manifest significant emotional, behavioral, and social problems. Although directly treating these children may be ideal, many parents are very reluctant to allow the child to take part in individual or family therapy. Preliminary research suggests that Learning Sobriety Together (LST; the brand name of Behavioral Couples Therapy for alcohol and drug abuse), a comprehensive psychosocial intervention for substance abuse that focuses both on reducing substance abuse and improving couple functioning, may provide an entry point into the family system from which to benefit children in these homes. To address this we will conduct a randomized clinical trial (RCT) to compare the emotional and behavioral adjustment, beliefs about aggression, and serious negative behaviors of youth ages 8 to 16 (as rated from mothers, fathers, teachers, and children themselves) whose drug- abusing fathers and non-substance-abusing mothers take part in LST as compared to youth whose fathers take part in an equally intensive individual-based treatment (IBT). We will examine whether LST is associated with significantly higher levels of adjustment (e.g., fewer internalizing and externalizing symptoms, less acceptability of aggression, less delinquency, aggression/violence, and substance use) at post treatment and during the 12-month follow-up as compared to IBT; whether participation in LST will result in lower addiction severity, increase couple functioning, lower interparental conflict, improve parenting, reduce risk for child maltreatment, and improve parental psychological functioning as compared to IBT, whether changes in addition severity, dyadic adjustment, interparental conflict, parenting, and parental psychological adjustment during and after treatment will be associated with changes in children's adjustment; and whether changes in addiction severity, dyadic adjustment, interparental conflict, parenting, and parental psychological functioning will partially or fully mediate the direct effect of treatment condition (LST versus IBT) on youth outcomes. Finally, we will test a moderated-mediation hypothesis to determine whether adolescents experience a significantly weaker effect than preadolescents. We intend to use the information collected from the proposed study to refine and modify LST to enhance its positive effects on children and provide an option for agencies to support youth in these homes.